Derive Macro snec::ConfigTable

#[derive(ConfigTable)]
{
    // Attributes available to this derive:
    #[snec]
}

Generates necessary trait implementations to use a struct as a configuration table.

By itself, #[derive(ConfigTable)] won't do anything, as it requires additional markers to describe how exactly the struct will serve as a configuration table. Those markers are expressed using #[snec(...)] attributes. The following "Snec-commands" are supported:

• #[snec(entry(EntryMarker))] (one per struct field) — generates an uninhabited type which implements Entry and a Get implementation for it. EntryMarker is the optional name for the marker type which defaults to the field's name converted to camel case.
• #[snec] (one per struct field) — alias of #[snec(entry)].
• #[snec(use_entry(entry_marker))] (one per struct field) — only adds a Get implementation for the specified entry identifier, without generating the type itself. entry_marker is given as an absolute or relative path to the entry type, i.e. it's not necessary for it to be in scope.
• #[snec(receiver({receiver_expression}: ReceiverType))] (can be one per struct field and also one on whole struct) — sets the receiver used in get_handle implementations for one struct field or the default for the whole struct to be used with #[snec(entry)]. receiver_expression is any valid Rust expression used to create the receiver, executed in the context of the Get implementation on the config struct. The type, ReceiverType must be annotated explicitly. If this attribute is not present, the receiver defaults to EmptyReceiver, which does nothing when notified.
• #[snec(entry_module(module_name))] (one on whole struct) — sets the module name in which the entry types generated by #[snec(entry(...))] will be placed to module_name. The default value is entries.
• #[snec(entry_module_visibility(visibility))] (one on whole struct) — visibility specifier the generated module for entry marker types. Uses private visibility by default.
• #[snec(entry_module_attributes(...))] (one on whole struct) — any Rust attributes applied to the generated module for entry marker types. Those attributes can be any valid Rust attributes, which include ///-style and /** */-style documentation, but are restricted to outer attributes, i.e. #[...] and not #![...].

Example

#[derive(ConfigTable)]
#[snec(
    receiver(
        // We just use the name of the struct as an expression, since it is a unit struct
        {MyReceiver}: MyReceiver
    ),
    entry_module_attributes(
        /// The module containing attributes for `MyConfigTable`.
    ),
    entry_module_visibility(pub),
)]
struct MyConfigTable {
    #[snec]
    field_with_a_receiver: String,
    #[snec(
        entry,
        receiver(
            {EmptyReceiver::new()}: EmptyReceiver
        ),
    )]
    field_without_a_receiver: i32,
}
struct MyReceiver;
impl Receiver<entries::FieldWithAReceiver> for MyReceiver {
    fn receive(&mut self, new_value: &String) {
        println!("Received a new value: {}", new_value);
    }
}